This is my promised follow up to a recent thread started by Duane on leaky chain plate woes. My sailing buddy, Tony, and I (well - 95% Tony and 5% me) have spent hours debating and thinking about a redesign for the chain plates to hopefully eliminate leaking once and for all. Tony is at the stage of having an aluminum prototype made and plans to have a full set of stainless replacements made to be installed in the spring.
We plan to photo document the whole project and report back to everyone how things work out over the sailing season.
The attachment outlines our ideas and shows a preliminary prototype. We'd appreciate constructive ideas on what those of you with chain plate woes think about where we are so far.
For one thing, it sure helps to make winter go by quickly.
Cheers,
Rick Verbeek
1999 C36 Hull # 1763
Toronto
Rick Verbeek
Southpaws
1999 C36 #1763
Lakeshore Yacht Club
Toronto
| Attachment | Size |
|---|---|
 Redesign of Chain plates C34-36 from 1995 to 2003.doc | 90 KB |
Looks like a well thought out redesign. I'll be interested in seeing the final project and any issues discovered.
Looking at the pic of the original chainplate, mine are just slightly different. There are a pair of bolts drilled/tapped through the bottom plate into the shroud bar. When I was removing them to rebed, at first I thought the shroud bar was just bolted to the plate, but it is indeed welded, too. I can't figure what the bolts are for, unless it was to hold the bar in place during welding? Otherwise, mine looks like the one in your picture.
A couple questions.
The pics of the new design are in aluminum. I don't see a weld of the top plate to the shroud bar; is it underneath the plate, or just not done on the prototype?
Second, very uninformed question. I was always under the impression that welding weakened the metal. Is that a concern? Keep in mind my welding experience is limited to mild steel with an arc welder; I'd assume the welding would be done with an advanced welder (TIG, etc.). And I realize the current design is welded as well, just curious if it's a concern.
Also, with the toggle, would the current rod be too long? I don't recall how much of the lower end is threaded.
Again, a lot of good thought went into this, and thanks for posting...!!!!
Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay
If I'm looking at your pictures correctly, my chainplates seem to be attached somewhat differently. The plate covering the top of the deck is not welded to the chainplate; it's screwed in independently through the deck. This has the result that when the shroud pulls on the chainplate, it doesn't pull on this bar, meaning less flex. (I hope I'm making myself clear here.)
SF Bay
1998 C36
Rick & Tony:
I can fully understand your desire to improve the water resistant capability of the chain plates, but I would caution you to be very careful with what you are doing as the results of any assumptions could be catastrophic.
From my perspective, the OEM installation results in the chain plate being drawn up against the underside of the deck by rig tension if the tension rods are not properly adjusted. This provides a measure of redundancy in the rig. In your proposal, the rig tension will tend to pull the chain plate away from the deck under similar circumstances.
The other problem is the aluminum in no way will replicate the structural intgrity of the stainless steel construction of the OEM chain plates.
One option to help prevent water intrusion is to form a plasticene dam approximately 1/2" all around the chainplate on the deck and fill the contained area with an epoxy and filler mix to a 1/4" depth thus forming a raised boss around the chain plate. This raises the sealing surface 1/4" above the deck to shed water. Of course the plasticene only makes a mold for the raised boss, remove it once the epoxy cures. Then grind a bevel into the raised boss around the tab on the chainplate and fill it with sealant.
Good luck with your endevours.
Tom & Janis Grover
C36 #0949
SR/WK, M25XP
Midland, ON
I would also recommend caution from an insurance claim standpoint: The typical insurance company may have issues honoring your coverage in the event of a rig failure, since the OEM would no longer be involved.
Just my opinion after years of dealing with insurance and lawsuits.
Laura Olsen
Past Commodore
S/V Miramar
hull 938 (MKI 1989, TR,WK, M25xp)
Edgemere, MD
Guys just clean the area real well, countersink the holes and bevel the edges slightly then properly tension the rods and use butyl tape and through bolt the cover plates NOT screws... The chain plates on our CS-36 were still BONE DRY at year 31 after well over 50k NM of serious world cruising.
The problem is you need enough sealant thickness to accommodate the movement and a sealant that is actually flexible. Cured PU, PS or silicone (please don't use silicone:eek:) are nowhere near as flexible and accommodating of movement as butyl tape is.
For more info feel free to read this..
[URL="http://forums.sbo.sailboatowners.com/showthread.php?p=705340#post705340"]Bedding Deck Hardware With Butyl Tape[/URL]
I have solved a number of leaky chain plate issues on Catalina's with butyl... Nothing fancy just the old school way of doing it, before builders got lazy & cheap...;)
-Maine Sail
https://www.marinehowto.com/
That is exactly the way the chainplates on our 1990 C28 were built and I liked it better than what is on the 36. For sure though Tom's caution on the tension on the rods is right, this has to be correct, if it is not the sealant will get beat out and a leak will occur. The PO of our 28 had left the tie rods slack and 4 of 6 were leaking. But if this works for you, I'd sure like to know about it.
Thanks for all the very thoughtful replies and some excellent alternative solutions to the problem.
We offer the following responses to some the issues raised.
The top plate will be welded to the shroud bar. It's just not shown in our prototype. If the weld is done properly (we will have it professionally done) there should be no concern about the strength of the weld.
The final chain plate will be made of stainless. We are having an aluminum prototype made just for fitting purposes (much easier to make and much cheaper). The prototype in the photos is actually a wood one that is painted silver.
We gain about 2 inches on the threaded rod with the toggle. The solutions are to machine more threads onto the rod or to add a longer bushing to the end of the rod attached to the hull. There is plenty of space to accommodate the extra two inches.
We agree with Tom that the current chain plate design pulls up against the underside of the deck if there is a rod failure however unlikely this event is to occur. The new design retains the two bolts which would still hold the pate in place abeit now situated on top of the deck. To reinforce the holding power of our new design, one could consider a floating (not welded) plate on the underside of the deck where it would be through bolted and act as a backing plate. We will seriously consider adding this. We agree that a raised boss is also a great idea. If you have had success with this, please post any pictures you may have.
Thanks for the heads up on the insurance issue. We plan to look into this and report back on any issues that come up.
It's pretty hard to argue with "Maine Sail's" solution and reported multi-year success although the current cover plate is so rudimentary one wonders if a larger cover plate would be more robust. The advice to through bolt the cover plate is in our minds crucial. In fact one of us (Rick) might pursue this for his boat. The bevelling and butyl tape is something we wholeheartedly support as the sealant solution.
Lastly we definitely concur that the tension on the rods is crucial no matter what the chain plate design may be.
Looking forward to keeping everyone posted as the project proceeds.
Cheers, Rick and Tony
Rick Verbeek
Southpaws
1999 C36 #1763
Lakeshore Yacht Club
Toronto
As I mentioned on the other thread, the 28's design uses a hefty floating backing plate below the deck.
Thanks Bud, we will definitely check this out.
Rick
1999 C36 #1763
Rick Verbeek
Southpaws
1999 C36 #1763
Lakeshore Yacht Club
Toronto